You mentioned in your article on writing fight scenes that a good action screen should be told in the character's mind (viewpoint), but there's still a part which I hope you can clarify.
I want to write an overview of what is happening during battle. How do I do this?
One of the choices an author makes is what kind of viewpoint to use. In a novel like a fantasy with lots of action, the advantage of using an omniscient viewpoint is that you can give an overview of a big battle. The disadvantage is that all immediacy is lost because you aren’t in your main character’s head. Readers today prefer the immediacy of third or first person viewpoint because they want to feel what the character feels, see what he sees, etc. Omniscient is more cold, and closer to a camera watching the action.
You can’t switch back and forth between types of viewpoint at your convenience because doing this knocks the reader right out of the book, and that’s one thing you want to avoid at all costs.
If you use a single viewpoint in a big fight, you'll miss some of the action because one fighter can't see everything, but you'll have intensity. If it is a long battle and you have more than one viewpoint character fighting, you can switch to the other viewpoint character in another scene.
If you want the reader to know about what’s going on in the big battle, you can have your character end up on a hill above the fight so he can see how the battle is going, or he can talk to another character who relays this information.
Study novels you've enjoyed where the novelist has really drawn you in during scenes like this. Seeing how he/she did it is a master's class in writing.
One particular writer who does great fight scenes and battles is Ilona Andrews who writes the urban fantasy series about Kate Daniels. It is set in modern times, but the weapons are often swords, etc. The author is a husband and wife team, and the husband is ex-military, and it really shows in the fight scenes, not only in the action but in the strategy.